(377f) Mass-Coupled Cstrs – Cooperative Dynamics in Complex pH-Oscillatory Reactions

Oscillating reactions with an autocatalytic effect involving protons (pH-oscillators) are of general interest in with possible implications in functional dynamics of biological systems. We examine two inorganic pH-oscillators, the hydrogen peroxide?thiosulfate?Cu2+?H2SO4 (HPTCu) reaction and bromate-sulfite-ferrocyanide (BSF) reaction. We focus on experimental examination of cooperative phenomena in two interacting mass-coupled stirred continuous tank reactors (CSTR) and mathematical modelling of the observed dynamics.

Both reactions in a single CSTR show basic features of nonlinear dynamical behavior involving multiple steady states, spontaneous oscillations, hysteresis and excitability. While the BSF system behaves in agreement with a common situation characterized by a cross-shaped bifurcation diagram, the other system departs significantly from this situation and displays unusual excitatory and oscillatory patterns.

Two reaction cells are coupled via a membrane allowing for diffusion-like mass transfer. We study effects of the coupling strength on the system that is intrinsically oscillatory in one reactor and in a steady state or oscillatory mode in the second reactor when decoupled, depending on the adjusted flow rate. Dynamical behavior includes nonhomogeneous steady states, fully synchronized periodic regimes, multiple-periodic phase locked regimes as well as highly nonperiodic behavior.

Another situation of interest occurs when both reactors are excitable. By imposing external short pulsed perturbations to one of the reactors, the perturbed reactor may be excited and this signal may be transferred to the second one, depending on the coupling strength and the amplitude of the pulse. If the system is forced by periodically repeated pulses, the sequence of transmitted excitations displays a wide variety of temporal patterns, ranging from full transmission of the perturbation (signal) through the 2-cascade to partial transmission to propagation failure, depending on the coupling strength. In addition, the partial transmission regimes may display complex dynamics, which may be characterized as deterministic chaos.

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